Gravity doesn't work

Ah, so you want the TitleScreen object to do its animation, then go away while, at the same time, the FishMan object is added to the world. Correct? Another question: why do you add your Background1 object near the top of your world? Is that not supposed to be like a ground for your fishman to stand on?

Yeah. Also the Background1 image has a platform near the bottom of the screen, and the image is huge, so I had to center it in order for it to be perfectly alligned in the world.

That is the problem then -- the image is huge -- probably takes up the entire world. So, the onGround method will always return true. Meaning VSpeed will be -16 for every act step the "up" key is pressed (which, will usually be 3 to 4 act steps for a fairly quick pressing of the key). Maybe you should add a new actor to be the ground (even if its image is transparent). The image should be as wide as the world and maybe 40 pixels high. The actor should be centered horizontally in the world and placed near the bottom of it, top edge of image aligned with top edge of platform in image of Background1 object. Also, you may just want to draw the image you are using for the Background1 object onto the background image of the world and dispense with the Background1 object (and class).